Ken Knecht wrote:
What are the rotating dipoles I see here and there used for? I
suspect data but why not microwave? Among others, I see one on
the front of my supermarket, and four more on a pair of large
high advertising signs. I'm sure there are others if I'd look for
them. They are not very noticable.

They are about 4 - 6' long, metal, and turn about once every 5
seconds.

If they were on a ship or a naval shore installation, I'd say they sound
like ship radar antennas. But there's certainly no need for a ship
radar on a supermarket! So I suppose the "it scares away the birds"
explanation makes the most sense from here...
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com